1. Technical Field
The present invention relates to waterproof shoes and, more particularly, to a waterproof shoe made by the Goodyear process and having excellent waterproofness.
2. Description of Related Art
Work shoes made and stitched by the Goodyear process are called Goodyear shoes. These shoes, strong and durable, are suitable for use in factories as well as for hunting, firefighting, military actions, and so on, where strict safety protection is required. Goodyear shoes often feature superior waterproofness.
A conventional Goodyear shoe is made waterproof by immersing an upper of the shoe in grease or wax and applying a waterproof glue to a stitch seam of the shoe. Other patented waterproofing techniques for Goodyear shoes include, for example, Taiwan Patent Publication No. 325648, in which a formed pad (midsole) is bonded to a waterproof thin sole; and U.S. Pat. No. 6,637,131, in which an inner welt, an upper, and an outer welt are sewn together with a thread, and when an outer sole (outsole) is formed and fixedly provided at bottoms of the welts, a liquid plastic material yet to be formed penetrates into and fills up clearances around the welts so as to block water from entering the shoe through the clearances.
No matter which of the above waterproofing techniques for the Goodyear shoe is used, the stitching thread extends well into the shoe. Although waterproofness is achieved by applying the waterproof glue or by filling the clearances with molten plastic when forming the outsole, the waterproof effect is good only for a while. After the shoe is used for some time, gaps are bound to develop between the glue and the thread so that waterproofness is compromised. Furthermore, all the aforesaid waterproofing techniques are fragmentary waterproof treatments. For example, the above-referenced Taiwan Patent Publication No. 325648 only uses a waterproof thin sole whereas the midsole located at an inner surface of the shoe is made of paper and not water-resistant. Similarly, in the above-cited U.S. Pat. No. 6,637,131, as shown in FIG. 1, an upper 91, though made of a waterproof material, has an open bottom where a paper-made midsole 92 is passed through by a thread 93. In consequence, water infiltration is still likely to occur if the waterproof treatment is incomplete or after the shoe is used for a period of time. Moreover, in order to make a robust Goodyear shoe, an inner welt 94 and an outer welt 95 are provided on an inner side and an outer side of the bottom of the upper 91, respectively, and stitched in place by a thread so as to reinforce the upper 91 sandwiched between the welts. However, stitch seams thus formed must also be waterproofed. Thus, the entire manufacturing process of the Goodyear shoe is complicated and time-consuming and leads to a high production cost.